Filippo Dattola

20 March 2021
Rencontres de Moriond 2021 - Electroweak Interactions & Unified Theories

Abstract: A search for the flavour-changing neutral current decay B+ → K+ ν ν is performed with an electron-positron collision data sample corresponding to 63fb−1 collected at the Υ(4S) resonance by the Belle II experiment. A novel measurement method is developed, which exploits topological properties of the decay that differ from both generic bottom-meson decays and light-quark pair-production. This inclusive tagging approach has the benefit of a higher signal efficiency compared to previous searches for this rare decay. As no significant signal is observed, an upper limit on the branching fraction of B+ → K+ ν ν of 4.4 × 10−5 is set at the 90% confidence level.